A Doppler guided retrograde catheterization system.

A Doppler guided retrograde catheterization system was developed to accurately catheterize the aortic root and left ventricular chamber without X-ray. This system consists of a 20 MHz, 0.076 mm thick x 1.016 mm diameter pulsed Doppler crystal integrated into the tip of a 100 cm multipurpose triple lumen catheter. Two lumens (0.61 mm) are used for electrodes; a third lumen (1.245 mm) may be used for guidewire and pressure determination; and the system is attached to a flow velocimeter. In an aortic arch flow model, the principles of Doppler signal guidance were confirmed with flow toward the catheter tip demonstrating positive signals and flow away from the catheter tip demonstrating negative signals. The magnitude and polarity (direction) of the detected phasic and mean velocities were utilized to guide catheterization in six dogs. Using the reversal of Doppler signal polarity to indicate branch entry and manipulating the catheter so as to maintain maximal positive axial velocity, the Doppler catheter was successfully advanced from the femoral artery to the aortic valve. Branches detected by the Doppler system were confirmed by fluoroscopy. The aortic valve was audible when approached and the left ventricular chamber was recognized by its characteristic pressure waveform. The Doppler guided retrograde catheterization system offers new technology to perform left heart catheterization without X-ray and may prove useful in a variety of settings including the development of invasive ultrasonic diagnostic and therapeutic technology.

Functional chiral asymmetry in descending thoracic aorta.

To determine whether rotational blood flow or chiral asymmetry exists in the human descending thoracic aorta, we established the ability of color Doppler ultrasound to detect rotational flow in a tornado tube model of a vortex descending fluid column. In a model of the human aortic arch with a pulse duplicator, color Doppler was then used to demonstrate that rotational flow occurs first in the transverse arch and then in the proximal descending thoracic aorta. With the use of color Doppler esophageal echocardiography, 53 patients (age range, 25-78 years; mean age, 56.4 years) were prospectively examined for rotational flow in the descending thoracic aorta. At 10 cm superior to retro-left ventricular position, 22 of 38 patients (58%) revealed rotational flow with obvious diastolic counterclockwise rotation but less obvious systolic clockwise rotation. At 5 cm superior to retro-left ventricular position, 29 of 46 patients (63%) revealed rotational flow with a tendency toward systolic clockwise and diastolic counterclockwise rotation. At the retro-left ventricular position, 47 of 53 patients (89%) revealed rotational flow, usually of a clockwise direction, occurring in systole. Our data suggest that aortic flow is not purely pulsatile and axial but has a rotational component. Rotational flow begins in the aortic arch and is carried through to the descending thoracic aorta, where flow is chirally asymmetric with systolic clockwise and diastolic counterclockwise components. These data demonstrate an aortic rotational flow component that may have physiological implications for organ perfusion.

Aerodynamic evaluation of crystalloid and colloid flush perfusion for lung preservation.

To assess the effectiveness of pulmonary perfusion we evaluated the lung mechanics of 36 canine lungs in an isolated perfused working lung (IPWL) model. Four groups of lungs (n = 9 each) were preserved by pulmonary artery flushing with either high-potassium colloid (UW), high-potassium crystalloid (EuroCollins', EC), low-potassium crystalloid control (lactate), or low-potassium substrate-enhanced crystalloid (RPMI) followed by 130 +/- 10 min of cold storage. Ventilation remained constant (TV 10 ml/kg at 14 breaths/min with 5 cm H2O PEEP). Assessed data included lung resistance (R), timed expiratory volume (EV0.3 sec as %TV), lung compliance (C), elastic work (Wel), and flow-resistive work (Wres). Immediately following storage, R and Wel were similar for all groups (16 +/- 3 cm H2O/liter/sec and 149 +/- 18 gm/min). UW preserved lungs were less compliant (1.5 +/- 0.1 X 10(-2) liter/cm H2O) and required more inspiratory work (Wres 5.8 +/- 0.8 gm/min) compared to the low-potassium crystalloid (Lactate) group (2.0 +/- 0.1 X 10(-2) liter/cm H2O and 3.4 +/- 0.6 gm/min, respectively, P less than 0.05). For 3 hr of reperfusion, crystalloid lungs showed no significant change in R, C, Wel, or Wres. In contrast, R of the UW group increased significantly to 32 +/- 5 and 40 +/- 8 cmH2O/liter/sec at 1 and 3 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)